System and method for consistent paper movement

ABSTRACT

A system and method for consistent paper movement includes a pick/feed motor configured to rotate a pick/feed roller of a print engine to deliver a sheet of paper to the registration nip of a registration roller. A first sensor and a second sensor disposed in the paper path between the pick/feed roller and the registration roller detect the leading edge of the paper. A controller receives sensor data from the first and second sensors and compares the sensor data with expected times for receiving the sensor data. When the received sensor data indicates that the paper is lagging or leading, the controller calculates a period of time to drive the drive the pick/feed motor at a higher or lower speed to compensate for the lagging or leading of the paper.

TECHNICAL FIELD

The subject application generally relates to controlling the timing ofthe movement of paper in a print engine, and more specifically tocontrolling pick and registration motors to ensure proper registrationof an image on a printed page.

BACKGROUND

Document processing devices include printers, copiers, scanners ande-mail gateways. More recently, devices employing two or more of thesefunctions are found in office environments. These devices are referredto as multifunction peripherals (MFPs) or multifunction devices (MFDs).As used herein, MFP means any of the forgoing.

MFPs use paper trays to hold paper for printing user print jobs. When anMFP receives a user print job, pick rollers deliver individual sheets ofpaper from a paper tray to a set of registration rollers where theindividual sheet of paper enters the image transfer unit and an image isprinted on the sheet of paper. However, paper slippage and other factorsmay result in a sheet of paper not arriving at the registration rollersat the expect time, or arriving ahead of time. When a sheet of paperarrives late or ahead of time the image on the paper can bemispositioned or a paper jam can occur.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments will become better understood with regard to thefollowing description, appended claims and accompanying drawingswherein:

FIG. 1 is a block diagram of an embodiment of a paper feed system;

FIG. 2 is a diagram of the paper path for a print engine;

FIG. 3 is a timing diagram of a paper feed system;

FIG. 4 is a timing diagram illustrating deskew timing of the paper feedsystem;

FIG. 5 is a flowchart of example operations of an embodiment of avariable speed paper feed control system; and

FIG. 6 is a flowchart of example operations of an embodiment of a dualspeed paper feed control system.

DETAILED DESCRIPTION

The systems and methods disclosed herein are described in detail by wayof examples and with reference to the figures. It will be appreciatedthat modifications to disclosed and described examples, arrangements,configurations, components, elements, apparatuses, devices methods,systems, etc. can suitably be made and may be desired for a specificapplication. In this disclosure, any identification of specifictechniques, arrangements, etc. are either related to a specific examplepresented or are merely a general description of such a technique,arrangement, etc. Identifications of specific details or examples arenot intended to be, and should not be, construed as mandatory orlimiting unless specifically designated as such.

In an example embodiment, an apparatus includes a registration motorconfigured to rotate registration rollers of an associated print engine,and a pick/feed motor that is configured to rotate a pick/feed roller ofthe print engine to deliver a sheet of paper to the registration nip ofthe registration rollers. A first sensor and a second sensor disposed inthe paper path between the pick/feed roller and the registration rollerdetect the leading edge of the paper. A controller receives sensor datafrom the first and second sensors and compares the received sensor datawith expected times for receiving the sensor data. When the receivedsensor data indicates that the paper is lagging, the controllercalculates a period of time to drive the drive the pick/feed motor at ahigher speed to compensate for the lagging of the paper. When thereceived sensor data indicates that the paper is leading, the controllercalculates a period of time to drive the pick/feed motor at a lowerspeed, or stop the pick/feed motor, to compensate for the leading of thepaper.

Embodiments herein provide for varying the operation of the pick/feedand registration motors based on sensed paper positions as a sheet ofpaper is fed by the pick/feed rollers to the registration rollers toensure that sheets of paper arrive at the registration nip of theregistration rollers at the expected time. Delivery of sheets of paperto the registration nip at the expected time ensures proper operation ofthe print engine, helps to reduce the occurrence of paper jams, andensure proper registration of images when the sheets are forwarded bythe registration rollers to the image transfer unit.

With reference to FIG. 1, an example paper feed control system 100 ispresented. Paper 104 is picked up from a paper tray 104 by pick/feedrollers 108 and delivered to a registration nip of registration rollers114. The registration rollers 114 feed the paper 104 to the next stage116 in the print engine, for example the image transfer unit. The paperpath 106 takes the paper 104 past two sensors S1 110 and S2 112 thatprovide a controller 130 with signals about the position of the paper104 in the paper path 106. The controller 130 also receives signals froma pick roll encoder 118 associated with the pick/feed rollers 108.

The controller 130 controls the dual brush motor driver 120 that drivesthe pick/feed motor 122 and the registration motor 126. The controller130 sends Pulse Width Modulation (PWM) control signals to the dual brushmotor driver 120 along with a direction signal for each motor 122, 126.Varying the duty cycle of the PWM signal results in varying voltagesvalues at the output of the dual brush motor driver 120, where a 100%duty cycle results in the maximum speed and a 0% duty cycle stopsrotation of the associated motor 122, 126. The varying voltage changesthe speed of the associate motor 122, 126. The pick/feed motor 122drives the pick/feed rollers 108 through an associated pick/feed gearbox124. The registration motor 126 drives the registration rollers 114through an associated registration gearbox 128. The controller 130receives signals from encoders in the pick/feed motor 122 and theregistration motor 126. Control of the motors 122, 126 by the controller130 is explained in detail below with regard to FIGS. 2 and 3.

Referring now also to FIG. 2, a cross sectional view of the paper feedpath of a print engine 200 is illustrated, and corresponding timingdiagrams are illustrated in FIGS. 3 and 4. FIG. 4 is a partial diagramof FIG. 3 for illustrating with particularity the timing describedbelow. The paper path 206, illustrated by the arrowed lines, starts witha paper 202 being picked up by pick/feed rollers 208 from a paper tray204 when the pick/feed motor turns on in the forward direction asillustrated in FIGS. 3 and 4. Alternatively the paper 202 can be fedfrom a sheet bypass feed (not shown). The leading edge of the paper 202is directed through a separation nip that ensures that only one sheet ofpaper 202 is passed through to the registration rollers 214. As thepaper 202 is passed from the pick/feed rollers 208 to the registrationrollers 214, the leading edge of the paper 202 first encounters switchS1 210 and then switch S2 212, placing each switch 201, 212 in the onposition, illustrated as positions X and Y in FIG. 4. When the paperpasses S2 212, the registration motor turns the registration rollers 214in the reverse direction as illustrated by position Y in FIG. 4. Turningthe registration rollers 214 in the reverse direction facilitatesdeskewing of the paper 202. As the paper 202 is pushed into theregistration nip of the registration rollers 214, the pick/feed rollers208 continue to push the paper 202 forward and a bubble is formed by thepaper 202. The registration motor then turns the registration rollers214 in the forward direction as illustrated by position Z in FIG. 4 andthe paper 202 is moved to the next stage, for example to the imagetransfer unit. When the registration motor is turned in the forwarddirection, the pick/feed rollers 208 are turned off and only theregistration rollers 214 move the paper 202.

When operating normally, the leading edge of the paper 202 is deliveredto the registration nip at the proper time to allow both a short periodof time for deskewing and the paper 202 to moved forward at the propertime by the registration rollers 214. However, factors such as paperslipping can result in a paper 202 not arriving at the proper time. Tocompensate, the controller can vary the speed of the pick/feed motor tospeed up or slow down the paper feed process based on the actual versusexpected times that the leading edge of the paper 202 arrives at sensorsS1 110 and S2 112. By speeding up or slowing down the pick/feed motor,the controller can compensate for the leading or lagging andsubstantially or entirely eliminate the leading or lagging.

FIG. 5 is a flowchart of example operations of an embodiment of avariable speed paper feed control system 500. The variable speed paperfeed control system 500 advantageously permits paper feed control insituations where the pick and registration motors can be operated atvariable speeds. The process begins at start block 502 and proceeds toblock 504 where the expected times from the pick roller to S1, S2, andthe registration nip are calculated. For example, the expected times canbe predetermined and retrieved from memory, or calculated based oncurrent or predicted operation of the printer. At block 506, the pickmotor is turned on at the normal speed to pick a page of paper from thepaper tray. At block 508, the process waits until the leading edge ofthe paper picked from the paper tray passes the first sensor, S1. Oncethe paper passes the first sensor, S1, progress is made to block 510. Atblock 510, if the paper arrived at the first sensor, S1, after theexpected time that was calculated at block 504, then the paper isdetermined to be lagging and progress is made to block 512 where thepick motor speed is recalculated for a higher speed, after whichprogress is made to block 516. If the paper arrived at the first sensor,S1, before the expected time that was calculated at block 504, then thepaper is determined to be leading and progress is made to block 514where the pick motor speed is recalculated for a lower speed, andprogress is made to block 516.

At block 516, the process waits until the leading edge of the paperpasses the second sensor, S2. Once the paper passes the second sensor,S2, progress is made to block 518. At block 518, if the paper arrived atthe second sensor, S2, after the expected time that was calculated atblock 504, then the paper is determined to be lagging and progress ismade to block 520 where the pick motor speed is recalculated for ahigher speed. In an embodiment, in block 520 the deskew time can beincreased to allow time for the paper to arrive at the registration nipand be properly deskewed. Progress is then made to block 524. If thepaper arrived at the second sensor, S2, before the expected time thatwas calculated at block 504, then the paper is determined to be leadingand progress is made to block 522 where the pick motor speed isrecalculated for a lower speed. Because the paper is determined to beleading, the paper may reach the registration nip and start to bubblebefore anticipated. Therefore, in block 522, the deskew time can beadjusted so that the paper deskews properly. Progress is then made toblock 524 where after a fixed deskew time the registration rollers areturned to forward the paper to the next stage.

FIG. 6 is a flowchart of example operations of an embodiment of a dualspeed paper feed control system 600. The dual speed paper feed controlsystem 600 advantageously permits paper feed control in situations whereone or more of the motors is operable only using discrete speeds, suchas a high and a low speed, rather than variable speeds as for the motorsin the variable speed paper feed control system 500 of FIG. 5. As wouldbe understood in the art, the system can be adapted to motors capable ofmore than two discrete speeds, or combinations of motors capable ofvariable and discrete speeds.

Operation of the dual speed paper feed control system 600 begins atstart block 602 and proceeds to block 604 where the expected times fromthe pick roller to S1, S2, and the registration nip are calculated asdescribed above. At block 606, the pick motor is turned on at the normalspeed to pick a page of paper from the paper tray. At block 608, theprocess waits until the leading edge of the paper picked from the papertray passes the first sensor, S1. Once the paper passes the firstsensor, S1, progress is made to block 610. At block 610, if the paperarrived at the first sensor, S1, after the expected time that wascalculated at block 604, then the paper is determined to be lagging andprogress is made to block 612. At block 612, the pick motor speed isoperated at high speed for a calculated period of time to advance thepage, after which the pick motor speed is returned to normal speed.Progress is then made to block 616. If the paper arrived at the firstsensor, S 1, before the expected time that was calculated at block 604,then the paper is determined to be leading and progress is made to block614. At block 614, the pick motor speed is paused for a calculatedperiod of time to slow transfer of the page, after which the pick motorspeed is returned to normal speed. Progress is then made to block 616.

At block 616, the process waits until the leading edge of the paperpasses the second sensor, S2. Once the paper passes the second sensor,S2, progress is made to block 618. At block 618, if the paper arrived atthe second sensor, S2, after the expected time that was calculated atblock 604, then the paper is determined to be lagging and progress ismade to block 620. At block 620, the pick motor speed is operated athigh speed for a calculated period of time to advance the page, afterwhich the pick motor speed is returned to normal speed. In anembodiment, in block 620 the deskew time can be increased to allow timefor the paper to arrive at the registration nip and be properlydeskewed. Progress is then made to block 624. If the paper arrived atthe second sensor, S2, before the expected time that was calculated atblock 604, then the paper is determined to be leading and progress ismade to block. At block 622, the deskew time is adjusted so that thepaper will deskew properly. For example, extra deskew time can be added.In a configuration, the pick motor can be briefly stopped and thenreturn to normal speed. Progress is then made to block 624 where after afixed deskew time the registration rollers are turned to forward thepaper to the next stage.

In light of the foregoing, it should be appreciated that the presentdisclosure significantly advances the art of paper feed control forprinters. While example embodiments of the disclosure have beendisclosed in detail herein, it should be appreciated that the disclosureis not limited thereto or thereby inasmuch as variations on thedisclosure herein will be readily appreciated by those of ordinary skillin the art. The scope of the application shall be appreciated from theclaims that follow.

What is claimed is:
 1. An apparatus, comprising: a registration motorconfigured to rotate a registration roller of an associated printengine; a pick/feed motor configured to rotate a pick/feed roller of theprint engine and deliver a sheet of paper to the registration roller; afirst sensor disposed in a paper path between the pick/feed roller andthe registration roller configured to detect a leading edge of thepaper; a second sensor disposed in the paper path configured to detectthe leading edge of the paper subsequent to the first detector; and acontroller configured to receive a sensor data from the first sensor,compare the sensor data with an expected time for receiving the sensordata, determine, based on the compare operation, when the receivedsensor data indicates that the paper is lagging, calculate a period oftime to operate the pick/feed motor at a higher speed to compensate forthe lagging of the paper, operate the pick/feed motor at a higher speedfor the calculated period of time.
 2. The apparatus of claim 1, whereinthe pick/feed motor is a variable speed pick/feed motor and wherein thecontroller is further configured to calculate the higher speed necessaryto compensate for the lagging of the paper.
 3. The apparatus of claim 2,wherein the controller is further configured to determine, based on thecompare operation, when the received sensor data indicates that thepaper is leading, calculate a second period of time to operate thepick/feed motor at a lower speed to compensate for the leading of thepaper, calculate the lower speed necessary to compensate for the leadingof the paper, and operate the pick/feed motor at the calculated lowerspeed for the second calculated period of time.
 4. The apparatus ofclaim 1, wherein the controller is further configured to determine,based on the compare operation, when the received sensor data indicatesthat the paper is leading, calculate a second period of time to stop thepick/feed motor to compensate for the leading of the paper, stop thepick/feed motor for the second calculated period of time.
 5. Theapparatus of claim 1, wherein the controller is further configured toreceive a second sensor data from a second sensor sensor, compare thesecond sensor data with an expected time for receiving the second sensordata, determine, based on the compare operation, when the receivedsecond sensor data indicates that the paper is lagging, calculate asecond period of time to operate the pick/feed motor at a higher speedto compensate for the lagging of the paper, and operate the pick/feedmotor at a higher speed for the second calculated period of time.
 6. Theapparatus of claim 1, wherein the controller is further configured todetermine a deskew time, rotate the registration motor and theregistration roller in a reverse direction to deskew the paper for thedetermined deskew time, and rotate the registration motor andregistration roller in a forward direction, after the deskew time, toadvance the paper to an image transfer unit of a printer.
 7. Theapparatus of claim 1, further comprising: a motor driver configured toreceive a pulse width modulated signal and a direction signal from thecontroller for each of the registration motor and the pick/feed motor,and drive the associated registration motor and the pick/feed motor inaccordance with the associated pulse width modulated signal and thedirection signal.
 8. The apparatus of claim 7, further comprising: amultifunction peripheral including the controller further comprising aprocessor and an associated memory, and a print engine comprising theregistration roller, the registration motor, the pick/feed roller, thepick/feed motor, the first sensor, the second sensor, and the motordriver.
 9. A multifunction printer, comprising: a print engine operableto perform a print operations, comprising a registration motorconfigured to rotate a registration roller, a pick/feed motor configuredto rotate a pick/feed roller configured to deliver a sheet of paper tothe registration roller, a first sensor disposed in a paper path betweenthe pick/feed roller and the registration roller configured to detect aleading edge of the paper, and a second sensor disposed in the paperpath configured to detect the leading edge of the paper subsequent tothe first detector; and a controller configured to operate the pick/feedmotor at a first speed, receive sensor data from the first sensor andthe second sensor, compare a receive time of the sensor data with anexpected receive time, determine, based on the compare operation, whenthe receive time of the sensor data indicates that the paper is leadingor lagging, calculate a period of time to operate the pick/feed motor ata second speed to compensate for the leading or lagging of the paper,operate the pick/feed motor at a second speed from normal for thecalculated period of time.
 10. The multifunction printer of claim 9,wherein second speed is selected from the group consisting of a variablehigher speed, a variable lower speed, a higher speed, and a stopped orzero speed.
 11. The multifunction printer of claim 9, wherein thecontroller is further configured to determine a deskew time, rotate theregistration motor and the registration roller in a reverse direction todeskew the paper for the determined deskew time, and rotate theregistration motor and registration roller in a forward direction, afterthe deskew time, to advance the paper to an image transfer unit of aprinter.
 12. The multifunction printer of claim 9, wherein the motordriver is configured to receive a pulse width modulated signal and adirection signal from the controller for each of the registration motorand the pick/feed motor, and drive the associated registration motor andthe pick/feed motor in accordance with the associated pulse widthmodulated signal and the direction signal.
 13. A method, comprising:driving, by a controller, a pick/feed motor at a normal speed to place asheet of paper in a paper path of a print engine; sensing, by a firstsensor, a leading edge of the sheet of paper; sending, by the firstsensor, a first signal to a controller associated with the print engine;sensing, by a second sensor, the leading edge of the sheet of paper;sending, by the second sensor, a second signal to the controller;calculating, by the controller, a first expected time associated withthe first signal and a second expected time associated with secondsignal; receiving, by the controller, the first signal; comparing, bythe controller, an arrival time of the first signal with the firstexpected time; determining, by the controller and based on the compareoperation, when the paper is lagging; calculating, by the controller, aperiod of time to operate the pick/feed motor at a higher speed tocompensate for the lagging of the paper; and operating, by thecontroller, the pick/feed motor at the higher speed for the calculatedperiod of time.
 14. The method of claim 13, wherein the pick/feed motoris a variable speed pick/feed motor and further comprising: determiningthe higher speed based in conjunction with the operation of calculatingthe period of time to operate the pick/feed motor at a higher speed. 15.The method of claim 13, further comprising: determining, by thecontroller and based on the compare operation, when the paper isleading; calculating, by the controller, a second period of time tooperate the pick/feed motor at a lower speed to compensate for theleading of the paper; and operating, by the controller, the pick/feedmotor at the lower speed for the calculated second period of time. 16.The method of claim 15, wherein the pick/feed motor is a variable speedpick/feed motor and further comprising: calculating, by the controller,the lower speed necessary to compensate for the leading of the paper;and operating, by the controller, the pick/feed motor at the calculatedlower speed for the second calculated period of time.
 17. The method ofclaim 13, further comprising: determining, by the controller and basedon the compare operation, when the paper is leading; calculating, by thecontroller, a second period of time to stop the pick/feed motor tocompensate for the leading of the paper; and stopping, by thecontroller, the pick/feed motor for the calculated second period oftime.
 18. The method of claim 13, further comprising: receiving, by thecontroller, the second signal; comparing, by the controller, an arrivaltime of the second signal with the second expected time; determining, bythe controller and based on the compare operation, when the paper islagging; calculating, by the controller, a second period of time tooperate the pick/feed motor at a higher speed to compensate for thelagging of the paper; and operating, by the controller, the pick/feedmotor at the higher speed for the calculated second period of time. 19.The method of claim 18, further comprising: determining, by thecontroller and based on the compare operation, when the paper isleading; calculating, by the controller, a third period of time tooperate the pick/feed motor at a lower speed to compensate for thelagging of the paper; and operating, by the controller, the pick/feedmotor at the lower speed for the calculated second period of time. 20.The method of claim 18, further comprising: determining, by thecontroller and based on the compare operation, when the paper is leadingor lagging; calculating, by the controller, a deskew time to compensatefor the leading or lagging; rotating, by the controller, theregistration motor in a reverse direction to cause the registrationrollers to deskew the paper for the calculated deskew time; and rotatethe registration motor in a forward direction, after the deskew time, toadvance the paper by the registration rollers to an image transfer unitof a printer.